A new poll by ComRes for the Sunday Mirror/Independent on Sunday released tonight shows how a significant minority of Tory voters would be prepared to lend their vote to UKIP.

The ComRes question was:

"Which, if any, of these parties would you seriously consider voting for at a General Election if it were held tomorrow?"

The poll found that 26% of Tory voters would "seriously consider" voting for UKIP. Other findings in the poll confirmed Britain's and – the Tory grassroots' – Eurosceptic stance. Britons want a cut in our contributions to Europe, they think we should leave if we don't get powers back, and so on. The openness of Tories voting for UKIP is probably the most important finding, however – especially as David Cameron heads off to the latest European budget summit next week. Downing Street's plans to build a Conservative majority in 2015 become a lot harder if even just a part of that 26% decide not to vote Tory.

At a ConservativeHome event on Monday, David Davis MP is expected to warn the party leadership that a failure to address the European issue could be a gift to Nigel Farage and his party.

Headline voting intention figures for the poll are Lab 43 / Con 31 / Lib 10. This 12-point lead is the highest Labour have enjoyed in a ComRes poll since March 2005.